1. Field of the Invention
The present invention relates generally to a building information extraction method that extracts the height and location of a building from an image captured by a manmade satellite or airplane and, more particularly, to a method of extracting three-dimensional building information using shadow analysis, which moves the contour of the roof of a building in the direction of the vertical line of the building after extracting the height of the building using a method based on a shadow projected onto an image, therefore the height and location of the building can be extracted from a single image.
2. Description of the Related Art
Since the launching of the first high-resolution manmade satellite, research into the extraction of information about geographical artifacts, such as buildings and roads, from high resolution satellite images has been conducted. In particular, research into the extraction of three-dimensional (3D) building information from aerial/satellite images have been actively carried out.
A representative conventional method of extracting the location and height of a building from images is a method using digital photogrammetry that measures the same location in two images from stereo images captured for the same area from different locations and calculates the 3D coordinates of the location based on the measurement results.
However, this method always requires two or more images, and requires a separate survey of a reference point and an accompanying complicated computing procedure in order to convert measured two-dimensional (2D) image points into 3D coordinates. Accordingly, the conventional technology has disadvantages in that a high cost is incurred and excessive processing time is taken.
Furthermore, in the field of aerial photograph/satellite image-based building information extraction, algorithms for determining whether a building exists and calculating the height of a building using a shadow have been developed (1. Cheol-Su Ye, and Koai-Hee Lee, 2000, Extraction of Building Information from Kompsat Satellite Image using Shadow Information, the journal of the Korea Society of Remote Sensing, 16(3):235-242; 2. Chungan Lin, and Ramakant Nevatia, 1998, Building Detection and Description from a Single Intensity Image, Computer Vision and Image Understanding, 72(2):101-121; and 3. Irvin, R. B., and D. M. McKeown Jr., 1989, Methods for exploiting the relationship between buildings and their shadows in aerial imagery, IEEE T. Systems, Man and Cybernetics, 19(6):1564-1575). However, these algorithms use shadows and measure the length of a shadow to calculate the height of a building, or to determine whether a building exists in an image, but do not use shadows to extract 3D building information.